Elastic moulding compositions of polyacetals and process for their manufacture

ABSTRACT

ELASTIC MOULDING COMPOSITIONS ON THE BASIS OF POLYACETALS ARE PREPARED BY REACTING COPOLYMERS OF TRIOXANE CONTAINING FREE AMINO GROUPS WITH POLYETHERS CONTAINING ISOCYANATE GROUPS. THE ELASTIC MOULDING COMPOSITIONS SO OBTAINED ARE THERMOPLASTIC AND DISTINGUISHED BY HIGH IMPACT STRENGH AND ARE USED ALONE OR IN ADMIXTURE WITH POLYACETALS TO FROM SHAPED PARTICLES.

United States Patent int. c1. cos 22/14 U.S. Cl. 260-67 TN 4 Claims ABSTRACT OF THE DISCLUSURE Elastic moulding compositions on the basis of polyacetals are prepared by reacting copolymers of trioxane containing free amino groups with polyethers containing isocyanate groups. The elastic moulding compositions so obtained are thermoplastic and distinguished by high impact strength and are used alone or in admixture with polyacetals to form shaped particles.

The present invention relates to elastic moulding compositions and a process for their manufacture. It has been described in German Pats. 838,826 and 831,604 to react polyesters containing terminal isocyanate groups with diamines. German Pat. 953,116 describes the reaction of toluylene 2,4 di-isocyanate with 3,3 dichlorobenzidine or with bis[3-ch1oro-4-amino-phenyl]-methane by which rubberelastic plastics are obtained.

The present invention provides a process for the manufacture of elastic moulding compositions of polyacetals wherein copolymers of trioxane containing free amino groups are reacted at temperatures within the range of from 50 to 230 C. with an amount at most equivalent to the free amino groups of the polyacetal of a polyether containing isocyanate groups.

Suitable copolymers of trioxane containing amino groups may be obtained in known ways by polymerization of mixtures of from 60 to 99.99% by weight of trioxane, 0.01 to 30% by weight of cyclic ethers or cyclic acetals containing nitro groups and 0 to 20% by weight of cyclic ethers or cyclic acetals and by following reduction of the copolymers containing nitro groups. Suitable reducing agents are for example molecular hydrogen in the presence of traces of palladium, platinum or Raney nickel, or hydrogen sulfide in the presence of ammonia, or hydrazine hydrate in the presence of ammonia or sodium dithionite, or sodium sulfide in the presence of piperidine. The reduction temperature is within the range of from 50 to 170 C. The reduction may be carried out in suspension as well as in solution. Suitable dispersing agents are for example alcohols or chlorinated hydrocarbons. Suitable solvents are for example benzyl alco- .hol, ethyldiglycol or o-dichlorobenzene.

As cyclic ethers or cyclic acetals containing nitro groups there are preferably used compounds of the general Formula I Suitable nitro compounds are for example o-, mor p-glycideoxy-nitro-benzene, 1-glycideoxy-2,4-dinitrobenzene, 1-glycideoxy-2,4,G-trinitro-benzene,

p- 1,3-dioxolano-4-methyloxy] -nitrobenzene, 1-glycideoxy-4-nitronaphthalene, 1-glycideoxy-2,4-dinitronaphthalene, 1-glycideoxy-2-methy1-4-nitrobenzene or 1-g1ycideoxy-2-methoxy-4-nitrobenzene.

Cyclic ethers and cyclic acetals are compounds of the general Formula II in which the radicals R to R are identical or different and stand for hydrogen atoms alkyl or radicals or halogen substituted alkyl radicals and R stands for a methylene or oxymethylene radical which may be substituted by alkyl or halo-alkyl radicals, n being a whole number from 0 to 3, or R stands for the radical n being 1 and m being a whole number from 1 to 3. The above mentioned alkyl radicals contain 1 to 5 carbon atoms and may be substituted by 1 to 3 halogen atoms, preferably chlorine atoms. There are preferably used cyclic ethers with 3 to 5 ring members, especially epoxides, as well as cyclic acetals with 5 to 11, preferably 5 to 8 ring members, especially cyclic formals of ot,wdiOlS with 2 to 8, preferably 2 to 4 carbon atoms, the carbon chain of which may be interrupted at intervals of 2 carbon atoms by an oxygen atom.

As cyclic ethers there may preferably be used ethylene oxide as well as propylene oxide and epichlorhydride. Glycol formal and diglycol formal as well as 4-chloromethyl-dioxolane are suitable cyclic acetals.

Suitable polyethers containing isocyanate groups are compounds of the general Formula III or IV in which R stands for the radical Y being hydrogen atoms or alkyl groups with 1 to 3 carbon atoms, n being a whole number from 2 to 4 and m being a whole number from 1 to 2500, preferably 4 to 500, and R stands for a linear or branched alkylene radical with 2 to 18, preferably 4 to 12 carbon atoms, or a bivalent cycloaliphatic radical with 6 to 12 carbon atoms or a bivalent aromatic hydrocarbon radical with 6 or 10 carbon atoms in the ring which may be substituted by (A),,, A being an alkyl radical with 1 to 3 carbon atoms and x a whole number from 0 to 4.

Suitable polyethers containing isocyanate groups are obtained by known processes by partially reacting polyethers, containing 2 or 3 terminal OH groups with diisocyanates in a manner such that only one isocyanate group respectively reacts with one OH group.

Polyethers of a molecular Weight within the range of from to 50,000, preferably 200 to 25,000 suitable for the reaction with di-isocyanates are for example polyethyleneglycols, polypropane diols, polybutane diols,

polytetrahydrofurane, polypropylene glycols, branched polyethers, which are derived for example from glycerol, as well as mixed polyethers from ethylene glycol and propylene glycol.

action with polyethers containing isocyanate groups elastic compressed plates are obtained which can be drawn oif without difiiculty from an aluminum foil after compression moulding.

The reaction between polyacetals containing amino 5 The following examples serve to illustrate the invengroups and polyethers containing lsocyanate groups may tion, but are not intended to limit it. be carried out in solution, in suspension or in the melt.

Suitable solvents are inert, polar organic solvents, for EXAMPLE 1 iififiiictfif iifit assessesamass: .0 50 grams A 60 of methane y 30 grams of d1oxolane and grams of 2,4-dinitroglycide- Suitable dispersing agents are inert, aliphatic aromatic oxyb-enzene Whlch contamed 178% NH2 groups aftgr reduction), 28 grams of a polyether, synthetized from polyor cycloallphatic hydrocarbons with 6 to 18 carbon atoms, glycol MW 2000 and t 01 lama 4 diisoc anate and O 5 for example n-hexane, cyclohexane or toluene. y y

. gram of trlethylene diamme were boiled under reflux for The reaction is carried out at temperatures within the 2 h ours in 500 mllllllters of 1,4-d10xane. After cooling r-ange of from 50 to 230 The temperature of the soluthe ol mer was oured into methanol while stirrin trons is preferably within the range of from 70 to 170 p y 0 After suction-filtration the polymer obtained Was boiled C., that of suspensions from 50 to 170 C. and that of with methanol Sucti O n fi1ter6 d and dri d the melt from 130m 230 0. e

It is advantageous to work in the presence of catalysts 20 Yi ld; 63 grams known in themselves in order to accelerate the reaction. S ft i i about 190 C Suitable catalysts are for example tertiary aliphatic or Reduced ifi viscosity 05 1 aromatlc ammes, example trlbutvl r e, py Characteristic values of the terpolymer A: N-methyl morpholine and tr ethylene diamlne, in amounts S ft i i about 13 5 Q of f t0 2% y Weight, p l y -Q to 10% Reduced specific viscosity 0.24 dL/g. by welght, calculated on the total reaction mixture.

The polyethers containing isocyanate groups are ad- The soften g Points were detefmllled a Kofler bankvantageously present in an amount at most equivalent to of the reduced P P VISCOSIW flied the free amino groups of the polyacetal; amounts equivmllllg'raffls of the P y were drssolved alent to f 40 t 80% f h amino groups are f 10 milliliters of butyrolactone which contalned 2% d1- ably u ed, phenylamine and the viscosity was measured at this tem- After the reaction has been terminated the polymer p which has been cooled is ground for elimination of the The term p s y MW 2000 1S P herein t0 mean tertiary amine, if the reaction has been carried out in a P y y havlng a molecular Welght of about 2000- the melt, and boiled with methanol or acetone until free Compress?cl Plates P p at of p lyfrom amine. If the reaction has been carried out in solumer w re brittle wh r as produ ts correspondingly pretion the precipitation of the polymer is completed after pared of the reaction product of terpolymer A and polycooling by addition of methanol, the polymer is suction ether (polyglycol MW 2000 and toluylene-2,4-d11soeyafiltered and freed from residual amine by boiling with nate) were elastic. methanol. If the reaction has been carried out in suspen- 40 In a manner analogous to Example 1 the following sion the polymer is suction filtered and washed with tests were carried out starting from grams of terpolymethanol or acetone until tree from amine. mer A, respectively:

Softening Amount Yield points Red Ex. Polyether with terminal isocyanate groups obtained from [g] {g.] 0.] [dl./g]

2 Polyethylene glycol MW 2000 and t0luylene-2,4-diisooyanate. 93 60 ca. 200 3.. Polyethylene glycol MW 700 and toluylene-ZA-diisooyanatc. ll 40 ca. 230 0.70 4 Polyethylene glycol MW 700 and toluyleue-2A-diisoeyanate. 17 54 ca. 230 0. 56 5 Polypropylene oxide MW 4000 and t0luyle11o-2,4-diisocyanato 32 04 ca. 200 6 Polytetrahydroiurane MW 1000 and toluylene-2,4-diisocyanato. 6!) 02 ca. 190 7 Polyethylene glycol MW 2000 and hcxane-1,6-diisocyanate 93 50 ca. 100 0. 8 Branched polyglycol MW 2500 and toluylene-2,4-diisocyanato 76 84 ca. 200

1 Not measurable; too viscous.

The decrease of the free amino groups of the starting EXAMPLE 9 polymer after reaction with polyethers containing isocyanate groups has been demonstrated in the infrared spectrum.

By the process in accordance with the invention elastic moulding compositions are obtained which can be processed in the thermoplastic range for example by extrusion, pressure moulding or casting into shaped articles such as plates, sheets or films, for example, to be employed for a variety of technical applications. The products of the invention are of high impact strength and are excellent compounding materials to be added to polyacetals in order to improve the impact strength of the latter.

For example, the starting terpolymer of grams of trioxane, 30 grams of dioxolane and 10 grams of 2,4-dinitroglycideoxybenzene containing 1.78% NH groups after reduction, cannot be drawn off as a continuous plate from an aluminum foil after compression moulding at 190 C. because of too much brittleness, but after re- Yield: 68 grams Softening point: about C. Reduced specific viscosity m 1.l5 dl./ g.

What is claimed is:

1. A process for making elastic polyacetals having improved impact strength which comprises reacting an acetal polymer having free amino groups with a polycther having isocyanate groups and selected from the general formula:

Y is hydrogen or an alkyl group with 1 to 3 carbon atoms, 12 is 2 to 4, m is 1 to 2500, and R is a linear or branched alkylene radical with 2 to 18 carbon atoms, or a bivalent cycloaliphatic radical with 6 to 12 carbon atoms or a bivalent aromatic hydrocarbon radical with 6 or 10 carbon atoms in the ring which may be substituted by (A),,, A being an alkyl radical with 1 to 3 carbon atoms and x being to 4, at a temperature of 50 to 230 C., said polyacetal polymer being the reaction product of 60% to 99.99% by Weight of trioxane, 0 to 20% of an oxygencontaining cyclic acetal or ether and 0.01 to 30% by weight of a compound of the formula R1 R2 (NO2)11 in which R is 2,3-epoxy-propyloxy or 1,3-dioxolano-4- methoxy radical, R is a bivalent aromatic hydrocarbon radical with 6 or 10 carbon atoms in the ring which may be substituted by (A) and/or (B),,, A being an alkyl radical with 1 to 6 carbon atoms, B being an alkoxy radical with 1 to 6 carbon atoms, x and y each being 0 to 4 and x+y being smaller than 5, and n is 1 to 3, with the nitro groups thereof reduced to amine groups, the proportions of polyacetal polymer and polyether being such that the isocyanate groups of the polyether are equivalent to to of the amino groups of the polyacetal.

2. A process according to claim 1 wherein the reaction is carried out in the presence of an inert polar solvent.

3. A process according to claim 1 wherein the polyether having free isocyanate groups is the reaction prodnet of an organic diisocyanate and a polyether having two or three terminal hydroxyl groups and a molecular weight 200 to 25,000.

4. An elastic polyacetal made by the process of claim 1.

References Cited UNITED STATES PATENTS 2,929,800 3/1960 Hill 26077.5 3,147,234 9/1964 Polly 260-67 3,248,373 4/1966 Barringer 26077.5 3,275,604 9/1966 Kray et al. 26067 3,425,992 2/ 1969 Yamauchi et a1. 26067 WILLIAM H. SHORT, Primary Examiner L. M. PHYNES, Assistant Examiner US. Cl. X.R.

26067 A, 77.5 AM, 77.5 AQ 

